9 and 4/5
Where is that on a ruler?
Which little line is it after the 9?
no the one near the 10 kinda.
Since US rulers are usually in inches rather than metric, it won't be exact. Unless one side of your ruler also has metric.
If there's a metric side, 4/5 = 8/10, so count to the 8th line. If your ruler only shows inches, 4/5 would be just a little past the 3/4" line.
Each ruler should have hashes at the inch mark and every 1/16th of an inch. This would include half, quarter and eighths. So, basically, 9 and 3/4 would be rather close to what you want. 4/5 and 3/4 are only 1/20 apart. Unless you're building a motor or something, that's not a big deal.
Sorry can't help you, but LOL, I don't feel so lonely any more. I never could grasp rulers or tape measures. I was awful at the "new math", fractions, decimals, and the list goes on and on.